Fuse plug



Aug. 2l, 1928. l 1,681,847`

W. H; FABREY FUSE PLUG Filed NOV. 4, 19,27

gmc/nto@ Patented ug. 21, 1928.

UNITED.. STATES PATENT orrics.

WILLIAM H. EAEREY, OE'SCHENECTADY, NEW YORK, AssIeNoR 'ro WEBER ELECTRIC COMPANY, or scHENEc'rAnY, NEW YORK, A'ooRroRA'rroN or NEW YORK.

FUSE PLUG,`

Application led November 4, 1927. Serial No. 231,069.

The present invention relates to electric fuse plugs, and particularly to the means for securing the contact shell yto the core in such devices.

` Devices ot this nature consist essentially oi a body or core element of porcelain or equiva-V lent insulating material, this body or core element consisting generally of a. head portion and a boss portion, which latter is surrounded by a contact shell. threaded both exteriorly` andinteriorly, the latter threads being an incident to the Jformer. Sometimes, according to prior practice, the boss portion of the core has threads molded in it for cooperation with the interior threads'ot the shell; again, the boss portion is frequently made smooth so that the shell will slip directly over it, and in this case, some further means must be provided to secure the two in permanent relation. In this latter practice, one method of securing the shell to the boss portion has been to provide the latter with indentations inwardly of the threaded portion of the. shell, the latter having an extension sleeve which at points in register with the indentations of the boss, is pressed into suchA indentations. Y l

The dificulty herehas been to insure that the indentations would be directlyin register with the pressing'tools, and due to this difficulty, loss from breakage has been extremely high.

The present invention is concerned with the provision of meansto obviate this pressing' operation in the'use of a smooth` or unthreaded cylindrical boss and an interiorly threaded shell. AThe invention will be described with particular reference to the accompanying drawings, wherein:

Figure 1 is a central longitudinal section ot a plugenibodying the present invention; Figure 2 is a section on the line 2--2 of Figure 1;

VFigure 3 is a side elevation ofthe core or bod y element with the shell removed; and

VFigure 4 is a perspective of the unit provided by the present invention for eii'ecting.

the union between the core and shell.

Referring to the drawings, 10represents generally' the core or body portion of the plug, which, as here shown, consists of what may betermed a boss portion 11 surmounted by an annular shoulder 12, which, in turn, is surmounted by an expanded annular head The Contact shell is portion 13. The core is provided with au axially extending chamber 14 which, at the chaintered extren'iity15 ot boss 11, is closed by means of a center contact element 16. Contact 'element 16 has an'inwardly extendmg sleeve portionv 17 which, at its inner extremity, is expanded over a. shoulder 18 so as to retain the contact element securely in position. Immediately beneath shoulder 12 the boss portion 11 is provided with a recess 19, as clearly shown in Figures 1 to 3, this recess being' substantially rectangular as viewed from the side as in Figure 8. The axially extending passage 2O is primarily incidental to the molding of recess 19, although under certain circumstances, this passage may be utilized as a conduit for the fuse element of the plug. In the embodiment as shown, however, a second axially extending passage 21 is provided, which passage leads to ai second recess 22 in the boss portion immediately below shoulder 12, and the end`23 of fuse element 24; is led into this second recess. The

other end 25 'of fuse element 2e is connected to the centercontact element 16. Recesses 19 and 22 are preferably substantially diametrically opposed.

As a primary means for securing the contact shell 26 toboss portion 11 which, as shown, has no threads tor cooperating with the interior threadsjof the shell, I provide a substantially arch-shaped element 27 adapted to be disposed in and seated against the back wall of recess 19 and to projecttheretroni in such a manner as to provide partial threads rfor cooperation with the inner threads of theshell. As here shown, element 27 is substantially lvl-shaped, the legs of this element resting on the bottom of recess 19 and being of such length as to position the shoulders outside of the peripheral bounds of the bossportion. i

' It will be readily apparent that element 27 can only bedisplaced radially and outwardly of the boss portion, and that when the shell is applied, :all displacement is prevented. This element., as shown, is formed of strip material, preferably resilient, and while its projecting portion may be 'provided with any desired number of corrugations the form shown hasbeen found to l'be entirely satisf.

factory, v Y

After shell 26 has been screwed into proper position on the boss through cooperation with vsage 2l. satisfactory connection, but Will also serve as a locking lug to prevent rotation of the shell relative to the tore due to its engagement with the sides of recess 22. This, however, is merely a secondary precaution, Since the frictional engagement of member 27 With the shell, enhanced by the resilient properties of the former, will be sufficient under most circumstances to retain the shell in proper relation to the boss.

To complete the plug, a transparent disk 29 is placed over chamber 14 in a shouldered seat 30, and linally an apertured cap 3l is crimped over head 13, the margins of the aperture overlying the edges of disk 29 in a manner to retain the latter in place.

Vhile I `have necessarily described a speciic Aembodiment of my invention, it is to be understood that I do not limit myself except as determined in the following claims.

I claim:

1. In an electric fuse plug, a core element including a substantially cylindrical boss portion, an interiorly threaded contact shell surrounding said boss portion, said boss portion being untlireaded and having a lateral recess, a filler piece seated in said recess and having a portion projecting therefrom into screw-engagement With the threads of said shell and a fuse element in said core element..

2. In an electric fuse plug, a core element including a substantially cylindrical boss portion, an interiorly threaded contact shell surrounding said boss portion, said boss proie tion having a lateral recess, a filler piece in said recess andhaving a portion projecting therefrom vinto screw-engagement with the threads of said shell, a fuse element in saidv core and a common means serving to secure an end ofv said fuse element and to hold the shell 4against rotation.

3. In an electric plug, a. core element in cluding a smooth substantially cylindrical boss portion, an interiorly threaded contact shell surrounding said boss portion, said boss portion having a lateral recess,l and a filler piece of strip metal in said recess having a rib projecting from said recess and extending circumferentially relative to said boss portion, said rib being in screw-engagement with Y the threads of said shell.

4l. In an electric plug, a core element including an Unthreaded substantially cylin drical boss portion, an interiorly threaded contact shell surrounding said boss portion, said boss portion having a lateral recess, and

a substantially arch-shaped filler piece in said recess formed of resilient strip material, the top of said filler piece projecting from said recess into screw-engagement with the threads of said shell.

5. In an electric fuse plug, a core element including a smooth substantially cylindrical boss portion, an interiorly threaded contact shell surrounding said boss portion, said boss portion having a lateral recess, a substantially arch-shaped filler piece insaid recess, the top of said iiller piece having a corrugation projecting from said recess and extending circumferentially relative to said boss portion, said corrugation forming partial threads in screw-engagement with the threads of said shell and a fuse element in said core element.

6. Inan electric plug, a core element including a smooth substantially cylindrical boss portion,l an interiorly threaded contact shell surrounding said boss portion, said boss portion having' a lateral recess, and a substantially resilient arch-shaped filler piece seated in said recess, the top of said filler piece having a corrugation projecting from said recess and extending circuinferentially relative to said boss portion, said corrugationV forming a partial thread in screw-engagement with the threads of said shell.

7. An electric fuse plug comprising a hollou7 core element including a. smooth substantially cylindrical boss portion, a central contact element at the 'extremity of said boss portion, an internally threaded contact shell surrounding said boss portion, said boss portion having a lateral recess, a filler piece in said recess and presenting a partial thread for cooperation With the threads of said shell, and a fusible element in said hollow core element and securedv to said central contact element and to said shell respectively.

8. An electric fuse plug comprising a hollow core element including an Unthreaded substantiallyv cylindrical boss portion, a cen-4 tral contact element at the extremity of said boss portion, ,an internally threaded contact shell surrounding Vsaid boss portion, said boss portion having two lateral recesses, a filler piece in one of said recesses and presenting a partial thread for cooperation with the threads of said shell a fusible element in said hollow core element connected at one. end to said central contact element and having its other end Adisposed vin said other recess, and means bonding said other end of said fusible element and said shell and therebv forming a locking lug to prevent rotation of said shell relative to said core'element.

In testimony whereof I have hereunto set my hand.

WILLIAM n. FABREY; 

